280 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



HENRICIA LEVIUSCXJLA (Stimpson). 



PI. 69, figs. 1, 2; pi. 70, figs. 1, 2; pi. 71, figs. 2, 3; pi. Ill, fig. 6. 



Linchia leriuscula Stimp.'son, IJoBton Journ. Nat. Hist., vol. 6 (No. 4), 1857, p. 529 (Puget Sound, 



Washington). 

 Chselaster cali/omicus Grube, 42 Jahresber. d. echles. Gee. f. vaterland. Cultur, 1865, p. 52 



(possibly refers to kviuscula). 

 Cribrella Ixviuscula Whiteaves, Canadian Nat., vol. 8, Dec. 20, 1878, p. 466; Trans. Roy. Soc. 



Canada, vol. 4, sec. 4, 1886 (1887), p. 117. — Sladen, Challenger Asieroidea, 1889. — ueLoriol, 



Mem. eoc. phys. et d' hist, nat., Geneve, vol. 32, pt. 2, No. 9, 1897, p. 14, pi. 2 (17), fig. 2.— 



Clark, Proc. Boston Soc. Nat. Hist., vol. 29, No. 15, 1901, p. 327. 

 Cribrella Ixviuscula crassa Clark, Proc. Boston Soc. Nat. Hist., vol. 29, 1901, p. 327. 

 Cribrella Ixvimcula atlenuata Clark, Proc. Boston Soc. Nat. Hist, vol. 29, 1901, p. 328. 

 Henricia leviuscula Fisher, Zool. Anz., vol. 35, March 29, 1910, p. 570. 



Diagnosis. — Kays five (rarely six). R = 3 to 7 r; R = upward to 100 ram. 

 General form variable, rays slender, more or less elongated or short and thickened, 

 cylindrical, tapering, blunt; abactinal pseudopaxillfe or groups of spinelets close- 

 set, typically larger than intervening papular spaces; spinelets very short, numerous, 

 and close-set, having as a rule a granidiform appearance under low magnification; 

 adjacent to adambulacral plates three very regular series of juxtaposed plates, the 

 median largest (inferomarginal), but the relative sizes variable; near base of ray 

 the uppermost (superomarginal) series bends upward in the interradial angle, and 

 the triangular area thus formed between the infero- and superomarginals is filled 

 with a variable number of smaller plates. Adambulacral plates wider than long, 

 typically with eight to twelve stubby spinelets in two transverse series, all of these 

 larger than adjacent actinal spinelets and increasing in size toward the furrow, 

 where two are considerably bigger than the rest. 



Description. — As the variations in this species are many, a composite description 

 would be unintelligible. For description, what is believed to be the typical form 

 from Puget Sound will be taken. Then some of the principal variations of this type 

 will be noted. R = 89 mm.; r=13 mm.; R = 6.8 r; R = 49 mm.; r=ll mm.; 

 R = 4.5 r. Scarcely any two have exactly the same proportions. Breadth of ray 

 at base is slightly greater than r. The abactinal pseudopaxillie or groups of spine- 

 lets are largest on the median radial area of disk and diminish gradually on either 

 side toward the superomarginal plates which are usually abruptly larger. The 

 plates are larger than the intervening papular areas which contain two to five 

 papulae on the dorsal surface, one or two on the side, and one on the actinal surface. 

 The plates are covered with minute short close-set spinelets, typically 30 to 60 on 

 the larger plates. There are two quite distinct variations even in otherwise nearly 

 similar examples. (1) The spinelets end in a clear, blunt, or more or less pointed, 

 glassy tip, below which are minute denticulations, more or less hidden by the tip, 

 variety A. (2) The spinelets are slenderer, and, as a consequence, less crowded, 

 ending in numerous minute denticulations, there being no sign of- the special glassy 

 tip, variety B. In the first variety the dorsal spinulation has a decidedly granuliform 

 appearance, especially as the glassy tips are more globular in some examples. 

 Under a glass the spinelets appear pearly or bead like (when dried). This form of 

 spine may be due to greater age, or to the action of waves. On the ventral surface 



